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TC Watch / 熱帶氣旋 > Selected TC Review / 重要熱帶氣旋回顧 > 201724W (KHANUN 卡努) [Refresh 更新]

201724W (KHANUN 卡努) - Profile 檔案

(First draft issued on October 23, 2017; final version issued on February 14, 2018)
(初稿於 2017 年 10 月 23 日發出，最後版本於 2018 年 2 月 14 日上載)

Brief profile of KHANUN | 卡努小檔案:

TC signals for Hong Kong & Track 香港曾經生效的熱帶氣旋警告和路徑圖:

Table 表:

Signal 信號	Date and time 日期和時間	Distance from HK 與香港的距離	Predicted movement 預測移動趨勢	Max. 10-min winds 中心最高十分鐘平均風速
	2017/10/14 (SAT) 10:40 HKT	SE 700 km	NW at 15 km/h	105 km/h (55 knots, STS)
	2017/10/14 (SAT) 19:10 HKT	SE 570 km	NW at 20 km/h	110 km/h (60 knots, STS)
	2017/10/15 (SUN) 08:40 HKT	SSE 260 km	WNW at 25 km/h	140 km/h (75 knots, T)
	2017/10/15 (SUN) 19:20 HKT	SW 290 km	W at 22 km/h	145 km/h (80 knots, T)
	2017/10/15 (SUN) 22:40 HKT	WSW 320 km	W at 20 km/h	140 km/h (75 knots, T)
	2017/10/16 (MON) 02:20 HKT	WSW 380 km	W at 20 km/h	110 km/h (60 knots, STS)

Figure 圖:

Percentile Ranks 百分等級:

IR imagery animation 紅外線雲圖動畫:

TC track from HKWW 本站的熱帶氣旋路徑圖:

TC tracks from HKO 天文台的熱帶氣旋路徑圖:

Past HKWW Bulletins 本站發佈

Please click here for bulletins on this tropical cyclone. 請按這裡。

Storm Development Overview 風暴發展概覽

Unless otherwise stated, all times below are in Hong Kong Standard Time (UTC+8)
除非特別註明，下文時間均為香港標準時間 (協調世界時加 8 小時)

An area of active convective activity persisted east of Luzon on October 11. The JMA issued a gale warning on the disturbance at 2 pm, while the JTWC issued a tropical cyclone formation alert at 2 am October 12. The HKO upgraded the disturbance into a tropical depression at 10 am, and the JTWC followed suit in the afternoon and assigned the storm number 24W to the system. The initial forecast called for a generally westward motion across northern Luzon before dipping south just west of the Philippines due to the storm's consolidation, and later moving west to west-northwest across the South China Sea as the subtropical ridge would then strengthen again.

24W moved west on October 12 as predicted, and more convections started wrapping around its centre. The JMA upgraded 24W into a tropical storm at 8 pm October 12, naming it KHANUN. KHANUN made landfall at northern Luzon in the small hours of October 13. It crossed the island in 6 hours and emerged into the South China Sea at around 8 am, dipping south at the same time.

Due to KHANUN's close proximity to the western Philippines, most of its convections were concentrated in its western periphery. The storm moved slowly in the night of October 13 and the morning of October 14 as it organized gradually. It intensified into a severe tropical storm and started to take on a northwesterly to north-northwesterly track that morning. It moved to a more northerly location than most numerical models and agencies had originally predicted.

In response to the strengthening subtropical ridge, KHANUN turned west-northwest early on October 15. It also intensified into a typhoon and could be seen developing a banding eye on satellite images. The storm was at its peak intensity near midday; the HKO further upgraded KHANUN into a severe typhoon. However, a strong surge of northeast monsoon was affecting southern China at that time and KHANUN was also drawing in cool, dry air continuously. It weakened into a typhoon before making landfall at the Leizhou Peninsula in the small hours of October 16. The storm was also subject to stronger vertical wind shear and land interaction, leading to an increased rate of weakening after landfall.

KHANUN emerged into the Gulf of Tonkin in the morning of October 16 as a tropical storm. Its deep convections were displaced quickly and the storm degenerated into an area of low pressure at afternoon under hostile atmospheric conditions in the Gulf.

10 月 11 日，一團活躍對流雲團於呂宋以東發展。日本氣象廳於當日下午 2 時對其發出烈風警報，而聯合颱風警報中心則於 12 日上午 2 時發出熱帶氣旋形成警報。香港天文台於 12 日上午 10 時將該擾動升格為熱帶低氣壓，而聯合颱風警報中心亦於下午跟隨，並給予風暴編號 24W。初時預測 24W 將大致西移並橫過呂宋北部，隨後因風暴自身整合而於菲律賓以西不遠處南移，繼而受副熱帶高壓脊增強牽引向西至西北偏西移動並橫過南海。

一如預測，24W 於 12 日西移，圍繞中心轉動的對流有所增加。日本氣象廳於 12 日下午 8 時將 24W 升格為熱帶風暴，並命名為卡努。卡努於 13 日凌晨時份登陸並橫過呂宋北部，6 小時後即上午約 8 時進入南海，同時有所南移。

由於卡努非常接近菲律賓西岸，其大部分對流集中於西半圓。風暴於 13 日晚間及 14 日日間移動緩慢，並逐漸整固。它當日早上增強為強烈熱帶風暴，並開始向西北至西北偏北移動。風暴北移幅度較大部分數值模式及官方機構初時預測為大。

因應副高增強，卡努於 15 日早段轉向西北偏西移動。同時，風暴增強為颱風，從衛星雲圖上可見它正在建立雲捲風眼。卡努於中午左右達到巔峰強度，香港天文台更將其升格為強颱風。可是，當時華南正受一股強烈東北季候風影響，卡努橫過南海時不斷捲進較乾涼的氣流。它於 16 日凌晨登陸雷州半島前減弱為颱風。其後，風暴受較高垂直風切變及陸地影響，登陸後減弱速度加快。

卡努於 16 日早上以熱帶風暴強度進入北部灣，其深層對流不斷被切離，最終於下午在嚴峻大氣環境下減弱為低壓區。

Weather in Hong Kong During Approach 風暴影響時香港天氣狀況

Link to relevant HKO weather report bulletins: 14/10 15/10 16/10
香港天文台相關天氣報告連結： 14/10 15/10 16/10

A surge of northeast monsoon was affecting southern China during KHANUN's approach. Locally, northerly winds prevailed on October 13 with generally fine weather. Winds picked up during the night; the Strong Monsoon Signal was issued at 4:20 am October 14 as the strengthening winds were primarily due to the monsoon rather than KHANUN which was still more than 700 km from Hong Kong at that time.

The Strong Monsoon Signal was in force until 8:45 am when fresh to strong winds were still observed in some parts of the territory. The cancellation of the signal was thought to pave the way for tropical cyclone signals. Indeed, the #1 Standby Signal was issued at 10:40 am when KHANUN was 700 km southeast of Hong Kong. At that time, KHANUN had started its poleward turn but was still moving at reduced speeds.

There were cloudy skies in the rest of October 14. The strength of the northerly winds stayed more or less constant, but with signs of an upward trend at night. The #3 Strong Wind Signal was issued at 7:10 pm as KHANUN moved to around 570 km southeast of Hong Kong and was moving northwest. The storm had also accelerated to a speed of around 20 km/h. The Observatory predicted that KHANUN would be within 300 km from the territory on October 15, and would consider the need for higher signals based on the storm's development.

KHANUN intensified into a typhoon and turned west-northwest overnight. However, under the effect of the monsoon, winds were still blowing in from the north and the sheltering effect was substantial. Rain set in around midnight as KHANUN's outer rainbands approached southern Guangdong. The effect of the monsoon was also evident from the air temperature, which dropped to a minimum of 20.4 degrees at the Observatory in the small hours of October 15.

Strong winds were observed in a number of places near dawn, while gale force winds were registered at offshore areas such as Waglan Island and Cheung Chau, and on high ground such as Tate's Cairn with occasional storm force winds. In response to the generally strengthening winds, the Observatory issued the Pre-No. 8 Special Announcement at 6:40 am October 15, indicating that higher signals would be issued by 9 am. The handling of laden cargoes were suspended at 6 am and ferry services were gradually suspended in the morning. The high wind management was implemented in the Tsing Ma Control Area and the traffic to the Hong Kong International Airport was exceptionally heavy.

The #8 Northeast Gale or Storm Signal was issued at 8:40 am when KHANUN was around 260 km south-southeast of Hong Kong. The #8 Signal was once again issued in October after typhoon HAIMA which affected Hong Kong in the same month last year. KHANUN continued to strengthen; within the next few hours, gales were observed at Cheung Chau, Green Island, Sha Chau, Tai Mei Tuk and Waglan Island, while Tate's Cairn was blowing sustained storm force winds. The Observatory upgraded KHANUN into a severe typhoon at 11 am as an eye emerged on satellite images within the tight banding cloud bands. However, it was evident from radar images that KHANUN's lower level circulation was asymmetric with convections in its eastern semicircle eroded away.

KHANUN was the closest to Hong Kong at around 3 pm as it passed at a distance of 210 km to the south-southwest. Winds turned northeast and stations such as Chek Lap Kok, Peng Chau and Tai Mei Tuk recorded the strongest winds at this time. As KHANUN moves to the southwestern quadrant, the wind direction veered towards the east between 3 pm and 5 pm. As the warm, moist airmass replaced the cool, dry northeast monsoon, a significant rise in the air temperature was observed in much of Hong Kong south of Tai Mo Shan; for instance, the temperature at the Observatory rose from around 22 degrees to 26 degrees during the afternoon, while the temperature at Chek Lap Kok rose to 28 degrees at night.

Winds finally started to diminish at night when KHANUN moved away and weakened. The Observatory issued the #3 Strong Wind Signal at 7:20 pm when KHANUN was 290 km away and had weakened into a typhoon. It also indicated that the water level was around 1 metre higher than normal and flooding could occur in low-lying areas during high tide (at around 8 to 9 pm). The #3 Strong Wind Signal was later replaced by the #1 Standby Signal at 10:40 pm; except for a few stations, winds had returned to below strong force level at that time. The #1 Standby Signal was cancelled at 2:20 am October 16 as KHANUN weakened into a severe tropical storm.

During KHANUN's approach, the government received 80 reports of fallen trees and 22 people sought medical assistance in the emergency units of public hospitals for storm-related injuries. More than 460 flights were delayed or cancelled. Due to the convergence of the northeast monsoon and a southeasterly airstream associated with KHANUN's outer circulation, the weather in Hong Kong remained unstable on October 16 and 17. The Amber Rainstorm Warning was briefly issued between 3:10 am and 4:20 am on October 17.

卡努靠近之時，華南正受一股東北季候風影響。本港方面，10 月 13 日主要吹北風，天氣大致良好。13 日晚本港風勢增強，但由於卡努當時距離香港超過 700 公里，風勢轉強與季候風關係較大，天文台遂於 14 日上午 4 時 20 分發出強烈季候風信號。

該信號維持至上午 8 時 45 分取消，但本港部分地區仍然吹清勁至強風程度北風。一般認為，天文台取消強烈季候風信號是為發出熱帶氣旋信號作出準備。果然，一號戒備信號於上午 10 時 40 分發出，當時卡努於香港東南約 700 公里，風暴已開始北移但移速較低。

14 日餘下時間香港大致多雲。北風強度基本上沒有太大變化，但晚間有增強跡象。天文台於下午 7 時 10 分改發三號強風信號，當時卡努移至香港東南約 570 公里，並向西北移動。卡努移速增加至每小時約 20 公里。天文台預計卡努將於 15 日在本港 300 公里範圍內掠過，屆時將因應風暴發展考慮是否改發更高信號。

卡努於當晚增強為颱風，並開始向西北偏西移動。但是，受東北季候風影響，本港仍然吹偏北風，屏蔽較為明顯。隨著卡努的外圍雨帶靠近廣東南部，午夜前後香港開始有雨。季候風亦令當晚氣溫偏低，天文台於 15 日凌晨錄得低溫只得 20.4 度。

破曉時份部分地區吹強風，而離岸地方如橫瀾島及長洲錄得烈風，高地如大老山更間中吹暴風。因應風勢增強，天文台於 15 日上午 6 時 40 分發出預警八號熱帶氣旋警告信號之特別報告，表示會於上午 9 時或之前改發更高信號。重櫃交收於上午 6 時起暫停，而渡輪服務亦於早上陸續暫停。受青馬管制區強風措施影響，青嶼幹線往香港國際機場交通一度非常繁忙。

天文台於上午 8 時 40 分發出八號東北烈風暴風信號，卡努當時於香港東南偏南約 260 公里。此為繼去年颱風海馬後再一次於 10 月發出八號熱帶氣旋警告信號。卡努於早上繼續增強，隨後數小時長洲、青洲、沙洲，大美督及橫瀾島錄得烈風，而大老山持續吹暴風。天文台於上午 11 時將卡努升格為強颱風，從衛星雲圖可見風暴緊密對流中心發展出一風眼，但同時從雷達圖可清晰見到風暴低層結構並不對稱，風暴東面的對流正受嚴重侵蝕。

卡努於下午 3 時左右最接近香港，於西南偏南方約 210 公里處掠過。本港風向漸轉東北，赤鱲角、坪洲及大美督等地於此時錄得最高風速。隨著卡努移至本港西南象限，風向於下午 3 至 5 時順轉至偏東。由於乾涼的東北季候風被濕潤溫暖的偏東氣流取代，本港大帽山以南大部分地區下午明顯升溫；香港天文台氣溫由 22 度上升至 26 度，而赤鱲角於晚間更上升至 28 度。

卡努於晚間逐漸移離並減弱，本港風勢開始回落。天文台於下午 7 時 20 分改發三號強風信號，卡努當時距離香港約 290 公里，並減弱為颱風。天文台亦表示水位高於正常約 1 米，漲潮時 (下午 8 至 9 時) 低窪地區可能出現水浸。下午 10 時 40 分，天文台改發一號戒備信號，除少數地區外風勢已回落至強風以下。隨著卡努減弱為熱帶風暴，一號信號最終於 16 日上午 2 時 20 分取消。

卡努襲港期間，政府共接獲 80 宗塌樹報告，22 人受傷並往公共醫院的急症室求診，超過 460 班航班延誤或取消。由於東北季候風與卡努外圍的東南氣流匯聚，16 至 17 日香港天氣仍然不穩定，天文台更曾於 17 日上午 3 時 10 分至 4 時 20 分發出黃色暴雨警告。

Image Gallery 圖片庫

Figure 1 - Satellite image of KHANUN at formation
圖 1 - 卡努形成時之衛星雲圖

Figure 2 - Steering flow chart at 8 am October 14
圖 2 - 10 月 14 日上午 8 時之駛流場圖

Figure 3 - Wind field analysis at 9:22 am October 14
圖 3 - 10 月 14 日上午 9 時 22 分之風場掃描圖

Figure 4 - KHANUN's forecast position as generated by the numerical model GFS. Note the prediction of storm force winds near Hong Kong.
圖 4 - 數值預報模式 GFS 預測卡努之位置，留意該模式預測香港附近吹暴風

Figure 5 - Forecast tracks from official agencies on October 12 (left) and October 14 (right)
圖 5 - 官方氣象台於 10 月 12 日 (左) 及 14 日 (右) 之預測路徑

Figure 6 - Time series chart of the delta-P values (difference in sea level pressures between Hong Kong and Chenzhou [dP(972)] and between Hong Kong and Shanghai [dP(S)]). Both values were rather high before and during KHANUN's approach.
圖 6 - delta-P 數值時間序列圖 (dP(972) 及 dP(S) 分別為香港與郴州及香港與上海間之海平面氣壓差)。留意卡努靠近前及靠近時兩值均較高。

Figure 7 - Satellite image of KHANUN near peak intensity. Image from weather-models.info.
圖 7 - 卡努於巔峰強度時之衛星雲圖。圖片來源：weather-models.info。

Figure 8 - HKO's estimates of KHANUN's wind radii at 2 pm October 15
圖 8 - 香港天文台於 10 月 15 日下午 2 時對卡努風圈大小的估計

Figure 9 - Radar images at 3-hour intervals from 8 am to 2 pm October 15
圖 9 - 10 月 15 日上午 8 時至下午 2 時每三小時之雷達圖

Figure 10 - Local wind disitribution maps at 3-hour intervals from 2 am to 5 pm October 15
圖 10 - 10 月 15 日上午 2 時至下午 5 時每三小時之本港風勢分布圖

Figure 11 - Wind speed time series at Cheung Chau, Sai Kung, Tate's Cairn and Waglan Island (top to bottom) on October 15
圖 11 - 長洲、西貢、大老山及橫瀾島 (上至下) 於 10 月 15 日之風速時間序列圖

Figure 12 - Time series of the air temperature, relative humidity and dew point temperature at the HKO on October 15-16 (top) and air temperature distribution over Hong Kong at 7:40 pm October 15 (bottom). Note the much lower temperatures in northern and northwestern New Territories than in other parts of Hong Kong.
圖 12 - 香港天文台於 10 月 15 至 16 日之氣溫、相對濕度及露點之時間序列圖 (上) 及 10 月 15 日下午 7 時 40 分香港分區氣溫圖 (下)。留意新界北部及西北部氣溫明顯較其他區域為低。

Figure 13 - Observed and predicted tides at Quarry Bay (top) and Tsim Bei Tsui (bottom) on October 15
圖 13 - 10 月 15 日鰂魚涌 (上) 及尖鼻咀 (下) 之預測及實測潮水高度

Figure 14 - Distribution of different air masses during KHANUN's approach. Image from Lorenzo.
圖 14 - 卡努靠近本港時不同氣團之分布圖。圖片來源：Lorenzo。

Winds Recorded at Reference Stations 參考站所錄得的風速

Charts and Figures 各項數據

Table 1: Track data from HKWW:
表一 : 香港天氣觀測站之路徑資料

Table 2: Maximum gust and hourly average wind speed recorded in Hong Kong from HKO:
表二 : 香港天文台公佈的各站最高每小時平均風力和陣風數據 (英文)

*The old wind station on the rooftop of Tap Mun Police Post is replaced by the new Tap Mun station on July 6, 2017.
*新塔門測風站在 2017 年 7 月 6 日取代在塔門警崗屋頂的舊測風站。

Table 3: Rainfall (in millimetres) contributed by KHANUN from HKO (figures in brackets are based on incomplete hourly data):
表三 : 香港天文台公佈的各站雨量資料 (英文) (方括號內之數據由不完整之每小時資料擷取)

Last Accessed 最近訪問日期: Fri Apr 19 2024 14:33:28 HKT
Last Modified 最近修訂日期: Mon Jul 24 2023